difficulties installing diff into housing

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difficulties installing diff into housing

Postby Chris Coker » Thu Jan 08, 2004 11:14 pm

I've just finished almost 3 hours of attempting to install the diff into the housing. It should just slide right into place, over the studs. It just seems to get cocked just a little, and hammering and using the nuts to crank it down hasn't really done much, other than stripping out some threads. :(

Very bad night in the garage.

At this point, I don't think I would ever attempt rear end ratio change at the track. Just too much hassle. I'm now considering taking the whole rear axle back out of the car, just so I can get the diff installed properly.

Any suggestions at this point would be appreciated. Things have been quiet lately, hopefully everyone is staying busy working on the cars, and having better luck than me! :shock:
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Postby Oilleak » Fri Jan 09, 2004 10:05 am

They can be a bear. I don't know that this will help you but I've done three recently and they have to go in just about perfectly straight. You can't muscle it in at all. Once it's gotten slightly cockeyed going in, it'll just get more stuck if you try to force it. Be carefull that you don't have any bent studs in the axle housing, that'll really make it fun.
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Bill Wessel
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Postby Bill Wessel » Fri Jan 09, 2004 10:30 am

Chris,

It shouldn't be a real problem. The hardest part (for me) is pressing the weight of the diff up into the housing from the floor while on my back.

Obviously, the axles must be out (but not necessarily removed) in order to slide the pumpkin in. And if one or more of your studs got bent, you'll have a problem. But I routinely change my diff to suit different tracks. It's a job I don't relish, but I've not had the problems you describe. Inspect the studs to see that they are straight (use two nuts tightened against each other, then unscrew the stud out... or use a small t-square) or take the diff back out and open the stud holes on the pumpkin just a tad. Clean up any burrs so you still have a good sealing surface and try again. If threads are stripped, you'll be replacing studs anyway....

Hope you find a solution.

Bill

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Rea

Postby Randy Carter » Fri Jan 09, 2004 2:50 pm

I also chagne rears routinely. the studs must be straight. If they are bent, the pumpkin gets cocked and jams. If the studs are straight it has not been a real problem.

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Postby Chris Coker » Mon Jan 12, 2004 10:34 pm

Just a quick update. I think the housing may have been tweaked a little when it was cambered. I've already made many iterations of painting the mounting flange of the diff with machinist's dye, sliding the diff over the studs, rocking it around, removing it, and doing some careful filing where I could see some interference.

Just to be sure, tonight I took out all the studs, and repeated the process. Sure enough, the diff won't quite slide into the housing. A couple more hours of careful filing, and I should have everything right again.

So far, I've left the axle housing installed in the car, but I've got it high enough in the air now that I can wiggle around under there a little better.

I've also been tackling some of my simpler project in the garage before I dive back into the axle problem again. Always nice to get a few 'successes' out of the way before spending time on something you know is going to be time consuming.
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Success

Postby Randy Carter » Tue Jan 13, 2004 7:30 am

Chris, you are right. A little success adds momentum for the next task. I am excited. I get my car back into my gargage this weekend. It has been out for the rear suspension work.

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Postby Oilleak » Tue Jan 13, 2004 8:06 am

Forgot about your cambered axle. that's a good thing to know as I'm probably going to do that myself. How much camber did you put on the axle?
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Postby Chris Coker » Tue Jan 13, 2004 8:51 am

I believe I have about 1.5 degrees of negative camber on the rear axle, and about 1/8" of toe-in. Still need to work out what that is in degrees. Don't know if those are the "right" numbers yet or not. I'll find out this year, on the track. Those numbers were recommended to me from the guy that did the axle work, and I believe it's how Huffaker has his axles set-up for his GT-4 Mini and FP Midget. You can apparently push negative camber up to 2 degrees, but at that point you tend to have problems with bearing life.
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Eureka!!!!

Postby Chris Coker » Tue Jan 13, 2004 9:56 pm

:shock: :shock: :shock:
Well, after about 8 hours total work, I have the diff mating properly with the axle housing. Lot's of iterations of painting the diff with machinist's blue, installing part way, taking it back out, and filing away the offending aluminum.

Here's the catch....The main area where I was having clearance problems, that I didn't discover until tonight....The bearing caps have little 'ears' that locate the back of the diff into the housing. These needed to have several thousandths filed off of them, and then everything slid into place.

Hopefully this will save the next guy to run into this problem a little detective work.

Machinist's Blue is the best invention since sliced bread.

I was also able to locate a nice replacement for axle housing studs. Get a set of ARP oilpan studs for a Mopar Hemi. You'll be all set, with some extra studs for spares.
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Re: difficulties installing diff into housing

Postby Ponder » Wed Aug 10, 2011 8:12 am

Sorry I haven't been to active on the board this year. Not sure why.

Anyway, I bought a 5.13:1 rear end from Mr. Wessel this winter and started installing it in May. Our fist autocross was on Memorial Day weekend. No problem, right? Drain the housing, disconnect the drive shaft, pull the axles, unbolt the old, lift up the new diff and "clunk". Hmmm. "Oh heck there was a thread on Chris's website about this, wasn't there." Went home to check. Yes there was. Read about his trials on fitting the old diff into this car.

Found some machinist's bluing at Fastenal eventually. That helped. Took the ring and pinion out to see if the housing was the problem or if it was the ears on the bearing caps. The housing didn't fit. Lots of filing and finally borrowed a big set of calipers from work and got a sense of where the interferences were and how big they were. Got the housing in, added the bearing caps and "Clunk". Worked on them until they fit. Added the ring and pinion and it straightened out the caps enough that they wouldn't fit again. Fil, file file. Finally the whole diff was in. Went to fit the axles back in and "clunk - ish. Pulled diff and axle and the axle slid in, ableit more closely fit than it did with the old diff.

Refitted the diff and tapped the axles in with a rubber mallet. Tapping may be a bit of an understatement.

Ran the car last week of July with the new diff. I think I had fifth fastest time of the day and only one ahead of me was in a slower class than me. So not too bad, but not as good as I had hoped (it never is) It's going to take a bit of time to get used to the extra busy-ness in the cockpit as a result of the extra shifting, but I think it'll be a nice improvement. That is, it will be if I ever get my head on straight. That would help.
I drank what? - Socrates


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